The best night vision scope for hunting: classification, popular brands, characteristics

Purpose

Such a sight can complement the equipment of both sporting and hunting rifles, even large-caliber ones, so it can be used to shoot even at long distances. Any night vision scope is equipped with high-aperture optics, which allows observation even on a moonless night. Due to powerful optics, aiming accuracy increases several times.

As a rule, there is also an aiming reticle. It is more convenient if it has a rangefinder scale - this will help more accurately determine the distance separating the shooter and the target. Most of the parameters in an optical sight are determined by an image intensifier - an electron-optical converter, but there are also digital sights. They are equipped with a CCD matrix.

Classification

Night vision devices are classified by generation. Generation 1+ and 1: models are the most affordable in terms of price and quality ratio for amateur devices. They have basic functionality and rather limited capabilities, which, however, does not prevent them from being in demand on the market. The positive aspects, judging by the reviews, include a very affordable price. Among the shortcomings, first of all, it is worth noting the blurriness of the image at the edges and sensitivity to light. Also, together with a sight from generation 1 or 1+, it is necessary to use additional powerful infrared illuminators. In models 1+, the resolution of the electron-optical converter is higher, and there is also protection against glare. In general, they produce a sharper image than generation 1, even at the edges of the picture. They are much more advanced and good for use even in an urban environment.

Operating principles of NVDs

Mentioned: both devices receive radiation; in the case of NVDs, the backlight plays a dominant role. Here's how the device works. A typical NVD contains the following parts:

1. Optical system.
2. Amplifiers.
3. Image construction subsystem.
4. Illumination path.

The rays enter through a professional eyepiece; a photoelectrode plate is fixed at the focus of the lens. The amplification path begins with it, the unit is placed in a pure vacuum so that air molecules do not interfere with the movement of electrons inside. Of course, the flow continues to be deflected by the Earth’s gravitational field; the effect is hardly noticeable over the length of the NVD body.

So, the light knocks electrons out of the circular photoelectrode plate, carried away by the positive potential of the microchannel amplifier. The device is worth talking about separately.

A round plate formed by multiple small honeycombs, indistinguishable to the naked eye. Overtaking the cell, an elementary particle knocks out a countless number of electrons, the process grows like an avalanche.

Expert opinion

Smirnov Alexander Stanislavovich

Wilderness survival instructor. More than 15 years of teaching experience

On the reverse side of the plate, in the area of ​​the honeycomb, a swarm of charges emerges, moving further onto the phosphor screen. Like a TV, only one color – green.

The shade was chosen based on the conditions of maximum sensitivity of the human eye and minimum mental stress.

The output optical system forms a picture for the eye. In binoculars, the flow bifurcates into both pupils.

In many ways it is more convenient due to the peculiarities of how the human brain works. The military often uses monoculars.

Single designs are combined with thermal imaging and night sights, which is more convenient for reconnaissance. Buying a night vision device with a magnification greater than 1 will cost money.

The devices do not work for magnification; they are positioned as a tactical advantage in real time.

Please note that there is a vacuum inside the amplifier tube, which does not deflect the linear movement of electrons. Otherwise, the picture will not only be blurry, it won’t work at all. Only the complete absence of air will allow the device to work. It should be clear to those who have encountered tube electronic devices. Rectilinear movement is due to the correct arrangement of potentials:

• At the photoelectrode the potential is lower than the intensifying plate. The highest voltage on the phosphor.

A similar principle is used by cathode ray tubes on old televisions. Household appliances use three colors of phosphor.

Next step

Often people put a lot of effort into finding a high-quality and functional, but at the same time relatively inexpensive item. If we take such a thing as a night vision scope for hunting, then models from generation 2 and 2+ are the “golden mean”. They work great in low light conditions, and also, when compared with similar devices of the previous generation, have a much longer range. A 2nd or 2+ generation electro-optical converter can provide good visibility even on a moonless night. However, it is not very suitable for an urban environment and shows its best performance when used in open areas, increasing shooting efficiency to 80-90%.

How to choose a night vision scope: main characteristics

To choose the best night vision scope for your purposes, you need to pay attention to the main characteristics of such devices, which determine image clarity, viewing range, ability to use in low light, and ease of use.

Lens diameter and aperture

The more light a night vision scope can collect for hunting, the more effective it is. A NVD with a large diameter lens collects the maximum amount of light and provides a bright, clear image.

Aperture is a value that shows the ratio of a lens' focus to its diameter. Modern night vision devices have an aperture ratio of about 1.5-2. The lower this value, the greater the aperture ratio of the lens and the clearer the image it can provide.

Magnification ratio

The magnification power of a night vision scope is usually indicated in its name. If it is, for example, 3X, this means that the object of observation located 150 meters from the hunter will look as if it is 50 m away. The magnification factor of the scope is determined by the characteristics of the lens and eyepiece, as well as the focal length.

line of sight

This parameter is indicated in the characteristics of the night vision scope in degrees. The higher its value, the greater the viewing angle the device provides. A good overview will help you navigate the area and allow you to cover a large observation area. It must be borne in mind that increasing the magnification of a night vision scope leads to a decrease in the field of view, so you need to find the optimal balance between these two characteristics.

Focusing

The technical specifications of a night vision scope may indicate the focusing range. These are the operating distances of the device at which it provides a good picture. You need to pay attention to this characteristic in order to choose a night sight that will best suit your tasks. If you have vision problems, you should also check the diopter adjustment of the night vision scope eyepiece before purchasing.

Resolution

High-resolution devices provide a clear picture with fine details. This parameter is measured in the number of visible strokes per millimeter. The latest generation NVDs have the maximum resolution; older models are significantly inferior to them in image quality.

Dimensions and weight of the night vision scope

These parameters become especially important when using a night vision scope for a long time. Better mechanics and optics are not the only differences between more expensive devices. They also feature a smarter, optimized design that keeps device size and weight to a minimum.

The best of the best

The third generation introduces the most advanced night vision devices to date. If the electron-optical converter in the scope is stated to be of this generation, you can be sure that the kit includes a photocathode based on gallium arsenide: this technique works excellently, even in extremely low light conditions. The third generation image intensifier tube has the highest resolution compared to previous ones, which guarantees a high-definition image. Details and quality are not lost even when the image is enlarged five times or more. The third generation night vision scope is an example of quality and functionality. The only drawback can be considered the rather high price for the entire line.

The appearance of the first NVGs

Despite Wikipedia’s statements that the championship belonged to the Nazis, the USSR also produced night vision devices. The work was carried out before the outbreak of World War II.

It was possible to introduce direction finders, sources of infrared radiation that play the role of navigation lights, into use in the Marine Fleet. The naked eye is powerless to notice the presence of infrared beacons; the secrecy of troop movements increased at night.

Work in the USSR was carried out by Research Institute 801, on the basis of which in 1983 the 1100 Orion department was created. Since 1991, it has been renamed SKB TNV.

Please note that people were also working on thermal imagers. Initially, both branches walked side by side.

We have provided a far from complete historical exposition of the formation of the industry, since we do not consider the issue under consideration to be important. The NVD development department included:

1. Lighting laboratory.
2. Photometric laboratory.
3. Power supply department.
4. Department of on-board instruments.
5. Department of ground-based instruments.
6. Department of physical foundations of night vision.
7. Navigation devices.
8. Thermal imaging department.
9. Design division.

The structure was engaged in the search for new methods for constructing images based on invisible parts of the spectrum. The part of electromagnetic oscillations visible to the eye is a small part of the global picture of the Universe.

The fact was used by Soviet scientists through research. The first illuminated night vision device was created in the early 50s. Of course, the conveyor belt supplied the defense industry. Few people were interested in a children's night vision device back then.

Surface-to-air and air-to-air missile guidance systems operate on the principle of direction finding of infrared radiation from a running aircraft engine. Regardless of what is intercepted, a helicopter, an airplane, another missile.

The first designs are quite cumbersome. What does a 45 kV power supply cost?

Slowly but surely, things moved forward towards ergonomicization, economization, and optimization. The developments of thermoelectric refrigerators, classified until the French conference in 1992, came in handy.

Expert opinion

Smirnov Alexander Stanislavovich

Wilderness survival instructor. More than 15 years of teaching experience

A significant shift in the design of night vision devices was given by the multi-alkali cathode. The device had a low dark current, did not require cooling, and had properties that were an order of magnitude superior to oxygen-cesium equivalents.

This is interesting: Algorithm for a citizen’s actions in the event of a threat or commission of a terrorist act

Advantages

You can buy a digital analogue of the 2nd generation for an amount of 40 thousand rubles, which is an order of magnitude lower than that of devices with a converter. Another advantage is the quality of the output image; it is at a high level both in the center and on the sides, but in digital format there is also a drawback: the image may “slow down” slightly. Thus, it can become a problem when using a digital sight to shoot at a moving animal or to shoot from an approach, but if you can let it “tune in” and hold the target at the front sight, then it will be in no way inferior to a device with a converter.

Dedal-180 HR (100)

The Daedalus night vision scope is very popular among hunters. Despite the fact that it has a first-generation converter installed, it is almost as good as the 1+ and even the second, however, the price of such a device is an order of magnitude higher than the minimum level - from 35 thousand rubles. This is a domestically produced night vision scope. Allows you to make shots from a distance of up to 150 meters. By equipping the device with an infrared flashlight, you can increase the distance to two hundred meters. It has a lens with a diameter of one hundred millimeters, which, together with a sensitive photocathode (about 350 μA/lm) and a powerful illuminator, produces high-quality images in low light and even on a moonless night.

Other characteristics

The device is suitable for both long-range shooting and short-range shots, including at a moving target, due to the field of view angle of 10°. Almost all major weapons can be equipped with a night vision scope. There are a lot of smoothbore or rifled weapons, but the Daedalus has three types of mounting: side, weawer and europrism, which allows it to be used with almost all models. This list even includes a 12 gauge Magnum. The device weighs a little - only 850 grams. Operating time on two AA batteries is up to sixty hours.

Pulsar Sentinel G2+ 3x50

The Pulsar night vision sight is designed for weapons with muzzle energy up to 6000 J. This is a hunting model from the popular Sentinel series, created on the basis of a domestic electro-optical converter type EPM66G2. It has a high light gain, and the sensitivity of the photocathode is also improved.

The device belongs to generation 2+ and can be used in various lighting conditions. There is a 3x magnification, which allows you to make aimed shots at a long distance (up to a kilometer). The Pulsar night vision sight in the G2+ 3x50 modification has a built-in infrared illuminator. The presence of a fast lens with a diameter of 50 mm and its internal focusing provide a high-quality image, even if the aiming distance is minimal (five meters). The field of view angle is 13 degrees. The device has a rangefinder reticle of the Mil-Dot type, and you can choose the color depending on the lighting conditions: red in good light, green if there is no contrast between the background and the target. The sight's moisture-resistant body is made of titanium, which creates an additional level of protection for the optics. The Pulsar Sentinel G2+ 3x50 is equipped with a control panel and a power supply with voltage stabilization. With the infrared illuminator turned on, the operating time without changing batteries is approximately seventy hours. There are several types of fastenings: Weawer Long, Europrism, side and Weawer Auto. The weight of the device is 1 kg, but may vary slightly depending on the choice of mounting. It should be clarified that this night vision scope will be optimal for a shotgun of any caliber, but may not be suitable for some models of rifled weapons. When choosing, you should focus on the maximum muzzle energy allowed for the device.

IR night vision devices - a history of generations

Having said A, say B... in continuation of the topic on IR night vision devices, I propose an article

Salikov Vyacheslav Lvovich

Source: magazine "Special Equipment"

The imperfection of one's own nature, compensated by the flexibility of the intellect, constantly pushed a person to search. The desire to fly like a bird, swim like a fish, or, say, see at night like a cat, came true as the required knowledge and technology were achieved. Scientific research was often spurred by the needs of military activity, and the results were determined by the existing technological level.

Expanding the range of vision to visualize information inaccessible to the eye is one of the most difficult tasks, as it requires serious scientific training and a significant technical and economic base. The first successful results in this direction were obtained in the 30s of the twentieth century. The problem of observation in low light conditions became particularly urgent during the Second World War. Its practical implementation made it possible to operate at dusk and at night without the use of visible light sources.

The first successes in the use of night vision technology, not yet realized by the public, made war by starlight a dream for military specialists. Enormous funds were spent to achieve results, allocated by both governments and leading companies in developed countries. People started talking about “victory over the night” already during the Gulf War. Subsequent conflicts in Yugoslavia and Chechnya made night combat an inevitable attribute of modern warfare.

Naturally, the efforts expended in this direction have led to progress in scientific research, medicine, communications technology and other fields. Adapted for individual use, analogues of military equipment are increasingly used for the needs of law enforcement agencies, security services, rescue, navigation tasks, among lovers of night hunting, etc. Changes in market conditions, resulting from global economic restructuring due to the fall of a number of political barriers in recent decades, have led to the rapid commercialization of modern high-tech products. As a result, the results of scientific and technical developments, based on knowledge of waves of the optical range not only of the visible region of the spectrum, but also of infrared (IR) radiation, have today become available in consumer goods.

Unfortunately, issues of night vision technology, which were openly discussed in wide circles of developed countries, in the USSR (Russia) were focused only on representatives of the military-industrial complex and direct developers. A brief retrospective of the history of night vision devices (NVDs) and a review of the current state of this segment of the optoelectronic products market are intended, in part, to fill this gap.

The operating principle of a classic NVD is based on the conversion of infrared radiation generated on the observed object by the glow of the night sky, stars and moon into visible light. A functional block diagram of the optical path of a modern NVD is shown in Fig. 1.

Rice. 1. Functional block diagram of the optical path of a modern night vision device

1. Observation object
2. NVD housing
3. Lens
4. Image intensifier tube with built-in MCP, VOE and VIP
5. Eyepiece
6. Batteries, usually AA batteries
7. Built-in IR illuminator

The image of the observed object through the lens is projected inverted onto the input glass of the electron-optical converter, which is a “high-vacuum lamp” with two flat ends, the input and output windows, respectively. A thin translucent layer of photosensitive material (photocathode) is applied to the inside of the input window, emitting electrons when absorbing light quanta. On the inside of the entrance window there is a layer of phosphor, a material that emits light when an electron hits it (screen). The transfer of electrons emitted by the photocathode is ensured by an electrostatic field, for which a voltage of several kV is applied to the photocathode and the screen. The image obtained on the screen is viewed through the eyepiece.

Modern image intensifier designs use a secondary emission amplifier or microchannel plate (MCP) installed between the photocathode and the screen to enhance the image. The MCP makes it possible to obtain an amplification of tens of thousands of times, and in some special-purpose image intensifier tubes – up to 107 times, which is sufficient for recording single photons.

The input and output windows of the image intensifier are made on flat glass or on a fiber-optic plate (FOP). To rotate the image 180°, a fiber-optic wrapping element (FOE), also known as a twister, is used as an output FOE. More complex designs use a binocular eyepiece or an additional lens wrapping element to rotate the image.

Despite the simplicity of the design and the minimum number of components, rather high and often contradictory requirements are imposed on each element of the night vision device. Obviously, the most complex and responsible NVD unit, which determines both its maximum parameters and price, is the image intensifier. The history of the birth and improvement of this unit should be considered indicative of the technocratic era.

“Glass of Canvas”

The first converter was developed by Holst and co-authors at the Philips research center (Holland) in 1934. It remained known as the “Holst glass”. Its diagram illustrating the principle of operation is shown in Fig. 2.

Rice. 2. Operating principle of the “Holst glass”

This image intensifier tube consisted of two glasses nested inside each other, on the flat bottoms of which a photocathode and a phosphor were applied. A high-voltage voltage applied to these layers created an electrostatic field, providing direct transfer of an electronic image from the photocathode to a screen with a phosphor. A silver-oxygen-cesium photocathode (or S-1), which had a rather low sensitivity (Fig. 3), although operational in the range of up to 1.1 microns, was used as a photosensitive layer in the “Holst glass”. In addition, this photocathode had a high noise level, which required cooling to minus 40 °C to eliminate it.

Rice. 3. Spectral sensitivity curves of image intensifier tube photocathodes

1. S-1; 2. S-20; 3. S-25; 4. S-25R (2+); 5.GaAs; 6. Near IR GaAs

These shortcomings made it possible to use the image intensifier only in active mode, that is, with illumination of the observed image by an IR illuminator. In addition, the image on the screen was blurry. The distance between the photocathode and the screen should be made as small as possible due to the scattering of electrons leaving the photocathode at different angles. In the “Holst glass” it was several mm and it was impossible to reduce it for technological reasons.

The appearance of the first image intensifier tubes in the pre-war situation aroused considerable interest. The “Glass of Canvas” was developed to the level of serial production by EMI (England), and from 1942 to 1945 several thousand pieces were produced (Fig. 4).

Rice. 4. The first production samples of the “Holst glass”.

Due to the “bouquet” of shortcomings of early image intensifier tubes, the first NVGs were distinguished by significant weight and size parameters and energy consumption, as well as low image quality.

However, they were actively used during the Second World War by all sides. The use of NVGs with IR spotlights by Germany to support the operations of combat vehicles has proven to be very successful. As a result, the Soviet army suffered serious losses in battles in the area of ​​the Hungarian Lake Balaton. The desire to equalize the chances and deprive the enemy of the advantage that had arisen forced the Soviet command to illuminate the battlefield with anti-aircraft searchlights when crossing the Oder River*. It should be noted that for the needs of the German army, more modern image intensifier tubes with electro-optical focusing were used, providing screen resolution of up to 20 microns, and in more complex versions even up to 1 micron.

American and English firms have achieved great success. Night sights for small arms “Sniperscope” are well known, successfully used during the American landing on the island of Okinawa. A rare photograph of American periscope glasses is shown in Fig. 5.

Rice. 5. Rare photograph of American periscope glasses

Note: * Author's opinion

Zero generation.

Advances in electron optics in the mid-30s made it possible to replace direct image transfer with focusing by an electrostatic field. Zvorykin, Farnsword, Morton and von Ardenna actively worked in this direction abroad, and in the USSR - G.A. Grinberg, A.A. Artsimovich. As a result, three- and then two-electrode systems were developed, providing amplification of the order of hundreds of times with simultaneous image wrapping (Fig. 6).

Rice. 6. Design of a three-electrode image intensifier tube.

1 – photocathode 2 – cuff 3 – body 4 – focusing electrode 5 – anode 6 – screen

Subsequent work led to the discovery of the “multi-alkali photocathode” (S-20), consisting of sodium and potassium arsenides doped with cesium. This photocathode has been the basis for most image intensifier tubes of almost all types for 40 years. An image intensifier tube with electronic image transfer and a multi-alkaline cathode today belongs to the zero generation, in the slang of specialists - “zero”. The most common representatives of this family in Russia are the V-8, the famous “eight”, and the K-4, which is of interest as a simple converter.

The efficiency of such image intensifier tubes can be determined through the amplification of the luminous flux hф (conversion coefficient).

hф(l) = Sk x U x g,

where Sk is the sensitivity of the cathode, usually expressed in μA/lm; U – applied voltage, V; g – screen light output, lm/W.

For example, for V-8, the integral sensitivity of a multi-alkaline photocathode can be 200 μA/lm, U - about 20 kV, g - about 30 lm/W. The luminous flux will be increased 120 times. In a similar way, you can determine the conversion coefficient of the monochromatic radiant flux hф(l) in lm/W, that is, at a specific wavelength. Spectral sensitivity is also indicated in lm/W.

Image intensifier tubes of this type have already been discontinued throughout the world and replaced by more efficient, but also more expensive converters of subsequent generations. The production of “zeros” that remained in Russia supported the national optical industry, which lost the market for its own products during the crisis of the early 90s. Quite quickly, mass production of cheap night vision devices was launched, filling the shelves. Today, 0th generation converters can be purchased for $20 apiece, and assembled with a high-voltage power supply (HVPS) for approximately $50. Combined with the low requirements for the optical components of such NVDs, their cost is $100-200. Insufficient characteristics allow such devices to be considered only as souvenirs or toys, which is often underestimated by buyers. However, they have found their niche in the market by defining the lower price range for NVGs.

The greatest disadvantage of an image intensifier tube with electrostatic image transfer is the sharp decrease in resolution from the center of the field of view to the edges due to the mismatch of the curvilinear electronic image with the flat photocathode and the screen. To solve this problem, they began to be made spherical, which significantly complicated the design of lenses usually designed for flat surfaces.

First generation

The development of fiber optics in the USA in the 60s made it possible to improve image intensifier tubes. Based on fiber-optic plates (FOP), which are a package of many LEDs, plano-concave lenses were developed, which were installed instead of the entrance and exit windows. The optical image projected onto the flat surface of the VOP is transmitted without distortion to the concave side, which ensures the pairing of the flat surfaces of the photocathode and screen with a curved electronic field.

As a result of the use of the VOP, the resolution became the same throughout the entire field of view as in the center. Image intensifier tubes with VOP and electrostatic focusing in mass production belong to the I-generation. In the manufacture of these image intensifier tubes, a sensitive S-20 photocathode began to be used. In addition, in the design of the first generation NVDs, mirror-lens lenses began to be used, which made it possible to improve the weight and size parameters.

Currently, first-generation image intensifier tubes are still used in night sights for hunting rifles and are successfully used where only conversion of near-IR wavelengths into visible light is required, for example, for visual inspection of the assembly of optical communication systems, in medicine, where YAGs are used -lasers with a radiation wavelength of 1.06 microns.

Multistage image intensifier tubes

While fiber optics technology was developing abroad, in the USSR cascade image intensifier tubes M.M. received priority. Butslova. The diagram of one of the most successful samples, U-72, is shown in Fig. 7. In this design, the total gain is equal to the product of the gains of all cameras and can reach 107 times.

Rice. 7. Design of a two-stage image intensifier tube with electrostatic focusing of electrons, type U-72.

The production of such image intensifier tubes was associated with significant technological difficulties, in particular, it required the use of only highly qualified glassblowers. In addition, the resolution at the edges of the field of view deteriorated to 2-3 lines/mm. However, the massive use of cascade converters ensured the tactical superiority of the USSR armed forces in the period 50-60.

The use of VOP for connecting cameras simplified assembly and improved image quality; the use of metal-ceramics instead of glass significantly increased the strength of the structure. Such image intensifier tubes were successfully produced by RCA, ITT (USA), Philips (Netherlands) and some others. They were not afraid of bright flares, and their only drawback should be considered their significant length along the optical axis.

The ten-year dominance of cascade image intensifier tubes was replaced by a rapid abandonment of their use and the displacement of image intensifier tubes of subsequent generations. Today, these converters have no commercial use; military equipment left over from the USSR period is equipped with modern small-sized image intensifier tubes. They were able to overcome the emerging technological impasse in the USSR only in the 80s.

Second generation

In the 70s, based on VOP technology, US companies developed a secondary emission amplifier in the form of a microchannel plate (MCP). This element is a sieve with regularly spaced channels with a diameter of about 10 microns and a thickness of no more than 1 mm. The number of channels is equal to the number of image elements and is of the order of 106. Both surfaces of the MCP are polished and metallized, and a voltage of several hundred volts is applied between them.

The principle of operation is well illustrated in Fig. 8. Getting into the channel, the electron experiences collisions with the wall and knocks out secondary electrons. In a pulling electric field, this process is repeated many times, making it possible to obtain a gain factor Nx104 times. To obtain MCP channels, optical fiber of different chemical composition is used. After obtaining the washer, the fiber cores are dissolved in chemical reagents.

Rice. 8. Operating principle of a secondary emission amplifier in the form of a microchannel plate.

The production of MCPs, like VOPs, is considered a high technology that ensures the production of small-sized and energy-efficient image intensifier tubes suitable for use in head-mounted NVGs, that is, glasses and monoculars. Image rotation in image intensifier tubes with MCPs, classified as generation II, is still carried out due to electrostatic focusing (Fig. 9). The prologue to the successful use of binocular glasses to support the operations of special forces of the armies of NATO countries was the model AN/PVS-5B from Litton (USA) (photo 1).

Rice. 9. Design of an image intensifier tube with an electrostatic lens

1 – photocathode 2 – anode 3 – microchannel plate 4 – screen

Photo 1. AN/PVS-5B glasses from Litton (USA)

At the end of the 70s, image intensifier tubes with an MCP of a biplanar design were developed, that is, without an electrostatic lens, a kind of technological return to direct image transfer, as in the “Holst glass” (Fig. 10). Similar designs, including multi-modal ones, are produced by Praxitronic (Germany). The resulting miniature image intensifier tubes, in a modern design, already classified as the II+ generation, made it possible to develop night vision goggles (NVGs) of a pseudo-binocular system, where the image from one image intensifier tube is split into two eyepieces using a beam splitting prism. The image rotation here is carried out using additional mini-lenses (photo 2).

Rice. 10. Design of a flat image intensifier tube

1 — photocathode 2 — microchannel plate 3 — screen

Photo 2. The device of the ONV pseudobinocular circuit (using the example of 1PN74).

1 — ONV body 2 — eyepiece 3 — wraparound lens 4 — mirror 5 — collimator (magnifying glass) with prism 6 — ONV body 7 — IR illumination 8 — image intensifier 9 — lens housing 10 — lens 11 — lens cap

The pseudo-binocular design is not only ergonomic, but also very economical, due to the use of one image intensifier, which is the most expensive unit - about 50% of the cost. The weight of such NVGs ranges from 500-700 g. Today, these are the most widely used NVGs, used in the armed forces and intelligence services of various countries around the world. For example, AN/PVS-7 in the USA and NATO, 1PN74 in Russia. It should be noted that mass production of such systems began in the USA in the mid-80s, and in Russia actually only now, although the development of the domestic model was completed in the early 90s.

Third generation

The next step in the development of the image intensifier tube was determined by increasing the sensitivity of the photocathode. It became possible as a result of purely scientific research. As a result of fundamental research that began back in the 70s, it was found that the optimal material for creating a photocathode is gallium arsenide, which can effectively emit electrons with initial radiation with a wavelength of 0.9 μm or less.

However, the implementation of AsGa-PC was hampered for a long time by the presence of an energy barrier that did not allow electrons to escape from the surface of the semiconductor layer (the potential electron affinity barrier). This problem was successfully solved by Scher and Van Laar, employees of the Philips Research Center, as well as Williams and Soyman, proposing the theory of OES (negative electron affinity).

Obtaining AsGa-PC is possible only under ultra-high vacuum conditions of the order of 10-10 - 10-11 mmHg, and the entire process must be carried out under the control of sophisticated diagnostic equipment. Due to the rapid oxidation of the photocathode surface in air, the third-generation image intensifier tube must also be assembled in a vacuum chamber using manipulators. As a result, the production of the third generation image intensifier tube requires more than 400 technological operations. All this determined the extremely high cost of these converters.

Initially, the industrial AsGa-FC technology was developed by the American company “Varian”, from which it was purchased for mass production by ITT Night Vision and Litton, leading companies in the United States, manufacturers of military NVGs for NATO needs.

The high characteristics of the III image intensifier allowed these companies to develop aviation binocular ONVs - ANVIS / AVS-6 for piloting helicopters, and AVS-9 for aircraft in night conditions at low altitude, this allows you to fly in close formation, recognize targets and obstacles on the ground.

Long-term scientific development and complex manufacturing technology, which determine the high cost of the third generation image intensifier tube, are compensated by the extremely high sensitivity of the photocathode. The integral sensitivity of some samples reaches 2000 mA/W, the quantum yield (the ratio of the number of emitted electrons to the number of quanta with a wavelength in the region of maximum sensitivity incident on the photocathode) exceeds 30%! (Fig. 3).

Of course, during the development of the image intensifier tube III, the achievements of technologies of all previous generations were applied, which made it possible to create a subminiature design. The standard diameter of the photocathode/screen is 18 mm, much less often 25 mm for sighting systems. High-voltage power supplies (VPS) are already built into the housing of such image intensifiers. Current consumption does not exceed 20 mA, with a supply voltage of 3V, which allows modern NVDs to operate continuously for almost a day using two ordinary AA batteries. In addition, these image intensifier tubes have very high reliability indicators (mean time between failures is about 10,000 - 19,000 hours).

The high sensitivity of the new photocathode made it possible to see in the worst conditions, called “cloudy starlight,” which means the presence of clouds and the absence of the moon. The illumination in this case is 5x10-4 lux. NVGs with image intensifier II were oriented to work in conditions of “natural night illumination” (NIL) - 5x10-3 lux, that is, in the light of stars without clouds and moonlight. Since 1992, ITT and Litton NV have supplied PVS-7B and ANVIS glasses with image intensifier III to the needs of the US and allied armies, according to multi-year industrial contracts Omnibus III (Omni IV since 1996 and Omni V since 1998).

Image intensifier tube IIIs are today considered a key military technology . Their presence creates a huge advantage for the army and aviation over a potential enemy in nighttime combat. At the moment, security services, law enforcement, and rescue services of developed countries are also carrying out large-scale purchases of these NVGs.

Besides the USA, only Russia produces converters based on AsGa-FC. The development of image intensifier III was greatly delayed due to some technological backwardness, which led to a crisis that became obvious with the outbreak of the war in Afghanistan. The embargo prevented the purchase of necessary equipment abroad. However, the existing obstacles were overcome.

Currently, two Russian companies “Kathod” (Novosibirsk) and “Geophysics-NV” (Moscow) produce image intensifier tubes III, offering them at prices of about $1500 - $1800, depending on the type of design and characteristics. “Geophysics-NV” is also the most advanced Russian company in terms of the development and production of aviation goggles. The 1PN74 goggles with image intensifier III used in the Russian army are produced by State Unitary Enterprise "Alfa" (Moscow), developed by SKTB TNV; for aviation needs, the same company supplies helicopter goggles "ONV-1". It should be noted that the distribution of such high-tech products is controlled by the state.

Image intensifier tube II+ and SUPER II+

The lack of domestic markets required to sell such expensive components as the III image intensifier has led most NVD manufacturers to question the ability to recover costs when putting them into production. An alternative was to improve the efficiency of existing converters. The development of this direction led to a return to the multi-alkali cathode, initially with increased sensitivity in the IR region (S-25), while maintaining the design solutions achieved in the III generation. Subsequently, a photocathode with particularly high sensitivity (S-25R) was developed (Fig. 3). On the basis of such cathodes, image intensifier tubes of II+ and SUPER II+ generations are produced today, respectively. A similar classification is used for the first generation.

Manufacturers of image intensifier tubes III admit that there are no fundamental differences in efficiency between the new Super II+ and III generation systems. The advantages of third-generation converters become obvious as these devices age, as S II+ photocathodes lose sensitivity (degrade) with use. The service life of such image intensifier tubes is about 3,000 hours, the cost is from $600 to $900, depending on the design.

Knowledge of the principles of image intensifier tubes and their production technology allows us to determine the main characteristics of NVGs and its expected cost. To quickly navigate within the framework of the considered classification, you should use the table, which summarizes the main characteristics of the image intensifier. However, for a more complete assessment, it is necessary to gain an understanding of the specific requirements for optical components and the design of such devices. The achieved quality of optical components did not limit the development of image intensifier tubes. The resolution limit, which determines the minimum angular dimensions of an observable object, is determined by the resolution of the MCPs used, that is, the diameter of the channels. Today, NVGs provide an average of 30-40 lines/mm; the best examples of image intensifier tube III, intended mainly for aviation, reach 64 lines/mm. The pore diameter in such MCPs is 5-6 microns with a thickness of hundredths of a mm. Due to their high fragility, these plates are extremely difficult to manufacture and process.

Only ultra-high-aperture lenses are used in the design of NVGs. The optimal lens is with a relative aperture (F-factor) of 1:1.4, the best models have 1:1.1 (for head-mounted systems with an image magnification of 1x, i.e. glasses, monoculars). Knowing the standard diameter of the photocathode, 18 mm for II+ and higher, it is not difficult to determine other basic parameters of modern NVGs: field of view angle 40°, focal length 25 mm. Today, lenses are produced with a field angle of 50° and even 60°, with a proportional reduction in focal length, which corresponds to the angle of the field of view of the eye with high clarity. Ergonomic requirements for minimizing the weight and size parameters of NVGs and image quality force the development of multi-component (up to 10, usually thin lenses), difficult to manufacture and, therefore, expensive lenses. The exception is “zero” lenses, which are usually inexpensive four-component designs. Differences in the anthropometric structure of the head forces developers to introduce an alignment mechanism based on the eyes (the distance between the optical axes of the eyes of different people varies from 56 to 72 mm), or to achieve significant diameters of the exit pupils of the eyepieces, more than 14 mm, which also complicates the design of head-mounted NVGs.

There are also problems when developing night vision sights. In particular, it is necessary to introduce an aiming mark and ensure an eyepiece eye relief of more than 50 mm, which leads to an increase in size and weight in the glass; high requirements for mechanical strength. Modern night sights and binoculars provide 3-5x image magnification at focal lengths of 75-120 mm and an aperture ratio of about 1:1.5. To use pseudo-binocular glasses as binoculars, afocal attachments are used that are mounted on the main lens (supplied as a set or upon special order). To reduce the weight of NVDs, mirror-lens lenses are often used, although traditional lens designs remain the most common.

In conclusion, it should be noted that the history of NVD is not limited to the achieved level. The continuous expansion of production and sales volumes, increased interest in new products from all participants in the high-tech market indicate broad prospects for night vision technology. Despite the fact that NVGs with an image intensifier III are capable of performing tasks in the darkest nights, active work is currently underway to develop both a IV generation image intensifier tube and to improve the circuitry of the NVGs themselves. Most of the work is related to improving the energy characteristics, design and expanding the functionality of devices. The development of photocathodes with sensitivity extended into the long-wavelength IR region is also of significant interest. A good result here was achieved by Litton, who developed the “infrared-advanced” image intensifier tube III, using which it is possible to detect the radiation of a YAG laser with a wavelength of 1.06 microns, used in all armies for ranging needs.

Table 1. Main characteristics of the image intensifier (selectively*)

* This table does not show a number of important characteristics, for example, resolution limit (lines/mm), current consumption (mA) and others. These characteristics can be taken into account in a similar way or as part of the product.

** Multi-chamber image intensifier tubes and image intensifier tubes with an increased photocathode diameter (25 mm versus 18 mm) are not taken into account; they require special NVD designs.

*** ENO - normalized “natural night illumination”, 5x10-3 lux, star light without the light of the moon and clouds; Image intensifier tube III - too, but at 5x10-4 lux, “cloudy” starlight, the sky is cloudy.

Unfortunately, the limited volume of the journal article does not allow us to cover in more detail the numerous, often dramatic events that accompanied the stages of development and improvement of night vision technology. A reader who has not come into contact with the world of night vision devices will undoubtedly be amazed to learn about the scale of influence of these famous works of technoculture on many military and political decisions of the second half of the twentieth century. Even specialists may be no less surprised by the scale of costs for the development and production of both traditional and newest NVD samples using almost all types of image intensifier tubes described. The widest range of NVDs of the same design, for example, indicates the lack of qualified marketing in the now international NVD market, with the exception of representatives of the USA, of course. It is quite possible that the problems that have arisen will help overcome the few articles devoted to the domestic and foreign fleet of night technology, as well as the prospects for its development, which the author plans to offer in the next issues of the magazine.

LITERATURE

1. Kurbatov L.N. A brief outline of the history of the development of night vision devices based on electronic optical converters and image intensifiers // Issue. Defense Technicians. Ser. 11. - 1994 - Issue. 3(142) - 4(143).
2. Koshchavtsev N.F., Volkov V.G. Night vision devices // Issue. Defense Technicians. Ser. 11. - 1993 - Issue. 3(138).
3. Goodman G. Modern night vision goggles used in the US Army. // Translation of an article in a journal. Armed Forces Journal International, July 1998, pp. 42-45.

Pulsar Digisight N770A

Pulsar digital sights are also produced. Digisight N770A is a device in the mid-price category. Can be used both day and night. Created on the basis of a CCD matrix, it provides effective shooting at a distance of up to 450 meters. The sight can be used with large-caliber weapons, the maximum permissible muzzle energy is 6000 J. Thus, the Digisight N770A can be installed on both rifled and smooth-bore weapons. The optical zoom is 4.5x, and the digital zoom is 1.5x. There is a built-in infrared laser illuminator with three power levels. Its light cannot be seen with the naked eye.

Pulsar Digisight N770A sights are equipped with a fifty-millimeter lens. The exit pupil is 67 mm away, which puts this scope among the best among devices in its class. The OLED display installed in the device is frost-resistant, has a resolution of 640 x 480 pixels and provides a clear image even at low temperatures. Image quality is also ensured by the SumLight and Contrast quick adjustment functions.

NVG with image documentation

In some cases, documentation (photography, video recording) of scenes, objects and their actions observed using NVGs is required.

The simplest solution is to join the NVG. instead of the eyepiece of a photo or movie camera. Some NVGs are equipped with adapters for attaching cameras, which can be easily done by the user of the device.

A more advanced and multifunctional system is the one in which the image from the NVD image intensifier screen is optically transmitted to a CCD matrix. Transmission is carried out using focons (fiber-optic “reducers” of the image) or lens “transfer” optics. The electronic circuit (“frame”) of the CCD matrix converts the resulting image into a video signal in analog and, if necessary, in digital form.

The video signal can be observed on a television screen (monitor), which is more convenient and less tiring than observation (especially long-term) through the NVD eyepiece. In this case, simultaneous recording to a VCR and transmission to several monitors for several operators is possible.

The video signal can be transmitted via cable (up to 200 m without intermediate amplifiers), or using a miniature transmitter built into the surveillance device, the signal of which is received on one of the channels of a regular TV.

The quality of such systems is determined by the number of television lines transmitted under a certain illumination of the observed scene.

When using NVGs with a zero-generation image intensifier tube, 300-350 lines are transmitted at an illumination of 0.01 lux; for NVGs with a second-generation image intensifier tube, the same number of lines are transmitted at an illumination of 1...5x10-3 lux, and with a third-generation image intensifier tube - at 1x10-3 4 - 5×10-5 lux.

Such devices can be equipped with adapters for connecting modern lenses for CCD cameras with remotely adjustable aperture (auto-iris), variable magnification (zoom) and subfocus to the NVD input. A device with such a lens and an image intensifier with a good AGC circuit provides almost round-the-clock (from moonless night to bright day) observation with the necessary documentation.

Converting the video signal into digital code gives the PHB+P3C systems additional capabilities. The resulting image can be recorded with a digital photo or video camera, processed to enhance contrast, eliminate light and dark defects, and painted in false colors.

A more complex complex of two NVDs with a CCD with special light filters, after digital electronic signal processing, creates an image of the observed night scene on the monitor in natural colors. This significantly increases the information content, speed and value of visual perception. Such a device, refuting the well-known proverb “all cats are gray at night,” was demonstrated at the IDEX-97 exhibition (Abu Dhabi) by the Belgian company Delft Sensor Systems. According to the developers, an image in natural colors increases the efficiency of detection and recognition of objects in night conditions by 30-60 percent.

In Russia, the development and production of systems based on NVGs and CCDs are carried out by the State Scientific Center "NPO Orion" together with a number of co-contractors.

Other Digisight Features

The necessary operating data is displayed at the bottom of the display so as not to interfere with observations. The main reticle configuration in the Pulsar Digisight N770A is a T-shaped reticle with a central dot. The color of the label can be changed between red and green, which is typical for devices from this manufacturer. The digital sight has a housing made of impact-resistant plastic and has a Weawer rail. An interesting feature of this device is the analog video output - this is an undeniable advantage of digital sights over devices based on electro-optical converters. Data from the Digisight N770A can not only be broadcast to a monitor, but also saved on a computer. The presence of a remote control allows all basic operations to be performed directly from a desktop computer or laptop.

Confrontation

One of the main disadvantages of all digital devices, including the Digisight N770A, is the operating time. If night vision optical sights can operate on a pair of batteries for several tens of hours, then the operating time of the digital analogue is only a few hours. Using four AA batteries, the Digisight N770A sight can operate for about 3.5 hours. However, external power supplies can be used to increase operating time.

Modern technologies provide a wide selection of different chargers, including those equipped with solar panels. External batteries with this feature can be very useful if a hunter is planning a long hike in an area where there is no electricity. Charging a digital device from solar energy will take considerable time, but good old optical devices can easily get by with such a source.

Comparison table of the presented models

Brief characteristics of the devices discussed above are listed below.

Sight selection

Most first-generation scopes are designed for use with 7.62-caliber weapons; some, however, can be installed on rifles with higher muzzle energy (up to 12 gauge). Devices of the second generation and higher can withstand large-caliber recoil, but the parameters should always be clarified when purchasing in order to eliminate errors. There is another important criterion - the range. When choosing night vision devices for a specific weapon and type of hunting, this parameter can be decisive. Approximate calculations are as follows: on a night when there is only a quarter of the moon in the sky, the viewing range with a first-generation device will be 100-150 meters. The second generation increases visibility to five hundred meters, and the third provides visibility up to 700-800 meters.

Typical night vision devices for security and safety systems

Let's look at portable NVGs first. These include night monoculars (NM) and night vision goggles (NVG).

Night monoculars

During observation, the NM can be held in the hand or mounted on a helmet or on a special universal belt headband. At the customer's request, it is possible to attach the NM to helmets of various designs using a special universal mount.

Rice. 1. NM “Alpha-90223” and the IR illuminator “Alpha-8111-2” mounted on its body using a dovetail mount (right)

NM "Alpha-9022" (Fig. 1) [2] has a human figure recognition range (RFH) at a level of natural night illumination (NIL) equal to 3×10–3 lux (cloudless starry night), Dpac. = 200 m, field of view angle 2? = 40°, increase Г = 1? to ensure normal spatial orientation. The device produces a high-quality image, uniform across the entire field of view, thanks to the use of a 2+ or third generation image intensifier in its design. The image intensifier tube uses a microchannel amplifier, a built-in high-voltage power supply, automatic brightness control and protection from powerful light sources. To increase the range to 300 and 400 m, the monocular can be equipped with optical afocal attachments with G = 2.5? and, accordingly, Г = 4?, an adapter that allows night video and photography (Fig. 2), as well as an external IR illuminator “Alpha-8011” (Fig. 3), which can significantly improve visibility through the NM in low conditions levels of natural night light and provide vision in complete darkness at a distance of up to 150 m. When working in “complete” darkness at short distances (up to 10 m), a built-in system of local IR illumination is provided at an illumination angle of 40°. The design of the NM provides aiming within ±4 diopters and lens focusing within 0.25 m–?. This refocusing is necessary for observing both distant and nearby objects (for example, a map of the area, a repair tool, a dashboard). The supply voltage is 2.5 V, the mass of the NM is 0.35 kg, its dimensions are 115 x 70 x 40 mm. The design of the NM provides the necessary protection from dust and moisture, and salt fog.

Rice. 2. Pairing the Alfa-9022 NM with a video camera using a special adapter

The LED IR illuminator “Alpha-8111” [2] is available in two modifications: “Alpha-8111-1” and “Alpha-8111-2”. They have emission powers of 35 and 20 mW at a wavelength of 820 nm with a supply current of 250–350 mA and 160–220 mA, respectively. Their remaining parameters are identical: illumination angle 4–9°, supply voltage 3 V, dimensions ?22?120 mm, operating temperature range –40…+40 °C. The illuminator is equipped with a mount that allows quick removal and installation on night vision devices. The IR illuminator "Alpha-8011" is designed to illuminate objects observed at night with insufficient natural light: a cloudy sky in the absence of light from the moon and stars, folds of the terrain, a forest, a basement, etc.

Rice. 3. LED IR illuminator “Alpha-8111-1”

To work together with NM or NVGs, laser target designators (LTs) mounted on individual weapons (for example, a machine gun) are used. The LC is designed for targeted shooting from firearms using a head-mounted night vision device in conditions of reduced natural light at night and at dusk. The LC serves to create a light spot (illumination spot) on the target, visible in the night vision device, but practically invisible to the naked eye. LC "Alpha-7115" (Fig. 4) [2] provides a smooth change in radiation intensity up to 50 times, depending on the specific conditions for observing the target and the illumination spot. Control of operating modes and discharge of power supplies is provided by built-in LED indicators. The LC has a radiation power of 2 mW, a working wavelength of 850 nm, an angular divergence of radiation of 0.5 mrad, a supply voltage of 2.4–3 V (two AA elements), a mass of 0.31 kg, and dimensions of 120×110×42 mm. LC is designed to operate in the temperature range –40…+50 °C and relative humidity up to 98%. At the customer's request, the target designator activation button can be rigidly mounted on the mounting bracket or placed on a flexible remote cuff.

Rice. 4. Laser target designator "Alpha-7115"

The sighting universal night vision complex KPU NV "Alpha-1962" (Fig. 5) [2] is designed for targeted shooting from firearms, reading maps, driving vehicles, repair work, etc. in low light conditions at night and in twilight. The complex is indispensable for special forces security forces. The complex includes:

• NM "Alpha-9022";
• LC "Alfa-7115";
• afocal-optical attachment with G = 4?;
• IR illuminator "Alpha-8111-2";
• helmet mount;
• Charger.

  Rice. 5. Night sighting system "Alpha-1962" in working position

NM "Alpha-9022" is mounted on a special headband or protective helmet. The fastening allows for quick transfer of the NM from the working position to the non-working position and vice versa. NM can be used independently of the helmet, “by hand”. In this case, it is equipped with an external IR illuminator “Alpha-8111” for vision in absolute darkness at a distance of up to 150 m, as well as an optical afocal attachment with G = 4? to increase vision range by 1.5 times. In addition, at the request of the customer, the NM can be equipped with an adapter that makes it possible to conduct night video and photography. The LC creates an IR spot of illumination, observed in the Alpha-9022 NM, but practically invisible to the naked eye. It is enough to give the weapon a position in which the illumination spot coincides with the target, and you can open fire. This allows you to fire from any position of the weapon and on the move. The charger provides charging of the batteries of the primary power supplies NM, CL and the illuminator from a voltage of 12 and 27 V, ~220 V, 50 Hz.

Rice. 6. Pseudo-binocular ONV PN-14K

Night vision goggles

There are binocular and pseudobinocular ONVs (Table 1) [1]. Binocular NVGs consist of two identical night channels under the operator’s right and left eyes. Each channel consists of a lens, an image intensifier and an eyepiece. The ONV provides smooth adjustment of the distance between the pupils of the eyes (base of the eyes) within the range of 52–72 mm. Binocular NVGs form a stereoscopic image. This is convenient for night driving of vehicles. However, pseudobinocular NVGs are most widely used, especially to ensure safety and security. They use one lens and one image intensifier tube. From the screen of the latter, the image is displayed on both eyes using a pseudobinocular microscope. Compared to binocular ones, such NVGs have minimal weight and cost. An example of pseudobinocular ONVs is the PN-14K model (Fig. 6) [3]. If, instead of a lens with a focal length of 27 mm, a mirror-lens lens with a focal length of 100 mm is installed, then the ONV data will be converted into night binoculars (Fig. 7) [3].

Rice.
7. Pseudo-binocular ONV PN-14K with a mirror-lens lens Table 1. Characteristics of various ONVs

Note: * - low profile, ** - pseudo-binocular, *** - in the form of binoculars after replacing the lens with a focal length of 27 mm with a mirror lens with a focal length of 100 mm.

A common disadvantage of the most common traditional NVGs is their significant longitudinal dimensions. Because of them, a large overturning moment occurs. It places stress on the operator's neck and facial muscles, causing fatigue. Therefore, the efforts of developers are aimed at creating low-profile (“flat”) NVGs with a minimum longitudinal dimension. Typical representatives of these are the ONV GN-2 from Simrad (Norway) [4] and the ONV Lucie from ANGENIEUX (France) [5]. The distance from the first surface of the ONV to the pupil of the eye does not exceed 80 mm, while for traditional ONVs this dimension ranges from 135 to 200 mm. Low-profile ONV 1PN105 has been created in Russia (Fig. [6].

Rice. 8. Low-profile ONV 1PN-105

In the USA, low-profile AN/GVS-21 NVGs have been created (Fig. 9) [7]. They are intended for special forces soldiers. Thanks to the eyepiece system, the ONVs have a low profile and, accordingly, a longitudinal dimension of no more than 80 mm. ONVs allow “end-to-end” vision due to the presence of a day channel with Г = 1?. They include a color OLED display module to which a thermal imaging image is transmitted. In this case, the observer simultaneously sees a combined image of the scene from the image intensifier screen and a thermal imaging image of the object being observed. Focusing limits 0.33 m–?, resolution 1.25 lines/mrad, eye base adjustment range 55–75 mm. A monocular version of the device is possible.

Rice. 9. Day-night NVG AN/GVS-21

Day-night binoculars

Day-night binoculars BDN-9S (Fig. 10) [7] are designed for round-the-clock visual reconnaissance of the area, detection and recognition of targets in daytime conditions and in ENO conditions. The daytime high-aperture channel BDN is built according to the classical stereoscopic scheme. The BDN night channel uses a small-sized sealed generation 2+ image intensifier tube with direct image transfer, microchannel amplification and a built-in high-voltage power supply. The brightness-enhanced image of objects on the image intensifier screen is then viewed by the observer using an optical system consisting of a projection lens, a reflector, wraparound lens systems and eyepiece units. Turning on and off the night channel BDN is done by turning the operating mode switch knob. The BDN rangefinder grid allows you to determine the distance to objects when working with both day and night channels. The characteristics of BDN-9S are given in Table 2.

Rice.
10. Day-night binoculars, model BDN-9 Table 2. Characteristics of day-night binoculars BDN-9S

Active-pulse night vision devices

All of the above NVGs cannot operate in conditions of reduced atmospheric transparency (haze, fog, rain, snowfall, dust storm, etc.) or when exposed to powerful light interference (headlights of oncoming traffic, spotlight radiation, etc.).
To overcome this drawback, laser active-pulse night vision devices (APNVDs) were created. Their principle of operation is based on pulsed illumination of the observed object with radiation from a pulsed laser illuminator and pulsed control (gating) of the image intensifier tube synchronized with it [1]. AI NVDs can operate in passive (without illumination) mode, in active-continuous mode (the illuminator is working, the image intensifier is not strobed) and in the active-pulse (AI) mode (the illuminator is working, the image intensifier is strobed). The characteristics of the AI ​​NVG models NNP-130 (“Polyus Research Institute” [9]) and “Titan 720” (“Mediton” [10]) are shown in Table 3. Externally, the AI ​​NVGs look the same as night binoculars with an illuminator. Thanks to the high degree of protection from light interference, AI NVDs can operate even in daytime conditions (in AI mode). Table 3. Characteristics of active-pulse NVGs